The present invention constitutes an improvement over the type of tire correcting apparatus taught in U.S. Pat. Nos. 4,016,020; 4,078,339; and 4,084,350 each of which discloses a system for measuring and correcting vibration generating forces in vehicular tires. The present invention also utilizes a multiple plane road wheel of the type disclosed in U.S. Pat. No. 4,211,109 wherein the periphery of the tire being corrected is in contact with a multiple plane road wheel comprising a series of uniform diameter wheel disks provided with sensor means to sense forces generated by the rotating tire in the peripheral areas of the tire contacted by each wheel disk, thereby enabling the user to isolate and measure the forces generated by the tire throughout the full width of its tread.
A principle objective of the inventions disclosed in the aforementioned patents, all of which are in the name of the present inventor, was to simulate the conditions encountered by the tire in normal use, i.e., when driven on a highway at normal cruising speed. In order to simulate actual operating conditions, the tire is mounted on a test wheel which is driven at the desired cruising speed, which might be 50-55 miles per hour in the case of a conventional automobile tire, or at a much higher rate of speed in the case of tires which are to be used for racing cars. The weight load which will be borne by the tire under normal conditions of use is simulated by pressing the road wheel against the tire at an applied force equivalent to that portion of the weight of the vehicle which would be borne by the tire.
While the arrangement just described provides valuable information for use in correcting and conditioning the tire, it does not take into consideration the fact that the tire is flexibly mounted with respect to the vehicle through the vehicle's suspension system. As the tire is rotated in normal use, peripheral non-uniformifies in the tire react against the vehicle's suspension system, which is dynamically loaded and hence reacts differently than if the tire were operating against a static load. It has been found that precise conditioning and correction of the tire requires evaluation while the tire is under a dynamic sprung load simulating the action of the vehicle's springs, as well as under static or fixed load.